The present invention relates to dispersible articles.
The ability to easily dispose of single use paper or nonwoven articles has been the objective of numerous programs. Such products call for good wet and dry strength of the product during use, but for the product to disintegrate in aqueous environments without clogging domestic waste disposal or septic systems. Products that would benefit from such properties include wipes, toweling used for wet or dry cleanup, napery, diaper and sanitary product covers, toilet papers and toilet seat covers.
Different technologies have provided dispersible paper and non-woven products. U.S. Pat. No. 5,916,678 uses multicomponent water-dispersible fibers. U.S. Pat. No. 5,935,880 discloses using a double recrepe (DRC) process to print a water-dispersible binder containing a divalent ion inhibiting agent. U.S. Pat. No. 5,948,710 coforms a fibrous nonwoven composite using a water-degradable reinforcing fiber matrix (for example, water soluble poly(vinyl alcohol) copolymer and fluff wood pulp composite). U.S. Pat. No. 5,500,281 and U.S. Pat. No. 7,776,772 disclose the use of water soluble fibers such as polyvinyl alcohol as a blend with other fibers. U.S. Pat. No. 5,252,332 uses a soluble binder such as polyvinyl alcohol.
U.S. Pat. No. 7,838,725 describes a mechanically weakened paper. The web contains two “mechanically weakened” layers that are joined by a water sensitive binder such as polyvinyl alcohol or starch. Salt sensitive polymeric (“ion trigger”) binders are insoluble in aqueous salt solutions but soluble when the salt solution is diluted, allowing the production of dispersible paper and non-woven products. An issue is that salt solutions can be irritating to sensitive skin. Preferably, these binders are relatively insensitive to calcium or magnesium ions. These salt sensitive binders are extensively disclosed; U.S. Pat. No. 5,312,883, U.S. Pat. No. 5,317,063, U.S. Pat. No. 5,384,189, U.S. Pat. No. 5,509,913, U.S. Pat. No. 6,423,804, U.S. Pat. No. 6,548,592, U.S. Pat. No. 6,586,529, U.S. Pat. No. 6,960,371, U.S. Pat. No. 6,994,865, U.S. Pat. No. 7,101,612, U.S. Pat. No. 7,276,459, U.S. Pat. No. 7,767,059, U.S. Pat. No. 7,989,545, U.S. Pat. No. 8,088,252.
U.S. Pat. No. 3,658,745 teaches crosslinking of polyvinyl alcohol with formaldehyde and glyoxal to provide a hydrogel. U.S. Pat. No. 8,133,952 teaches that a blocked glyoxal and polyvinyl alcohol can provide a curable aqueous composition. U.S. Pat. No. 4,279,959 teaches latex containing acrylamide functionality that is then modified with glyoxal that is useful for nonwovens. U.S. Pat. No. 7,732,057 provides a laminated veneer product containing a paper backing with a curable formaldehyde-free latex polymer.
U.S. Pat. No. 7,189,307 teaches a fibrous sheet comprising a topically-applied network of a cured binder composition resulting essentially from the cross-linking reaction of a carboxylated vinyl acetate-ethylene terpolymer emulsion and an epoxy-functional polymer. Example 11 in this patent discloses a binder which also incorporated glyoxal as a crosslinking agent in the latex formulation, using Kymene® 2064 (an epoxy-functional polymer) and Airflex 426 (a carboxylated vinyl acetate-ethylene terpolymer emulsion). Epoxy-functional polymers provide permanent wet strength and do not provide a dispersible non-woven or paper product. U.S. Pat. No. 7,229,529 describes a binder composition comprising 5-20 weight percent of glyoxal, glutaraldehyde or glyoxalated polyacrylamides as anti-blocking additives.
U.S. Pat. No. 7,678,228 describes a binder comprising a mixture of an azetidinium-reactive polymer, an azetidinium-functional cross-linking polymer and glyoxal, glutaraldehyde, waxes or sugars as anti-blocking additives. Azetidinium-functional cross-linking polymers provide permanent wet strength and do not provide a dispersible non-woven or paper product. U.S. Pat. No. 7,678,856 also discloses polymers that provide permanent wet strength and does not provide a dispersible non-woven or paper product. U.S. Pat. No. 7,767,059 describes bathroom tissue or facial tissue having strength regions and dispersability regions. U.S. Pat. No. 7,449,085 discloses absorbent paper products which have a combination of high absorbent capacity and a moderate to low rate of absorbency for hand protection. U.S. Pat. No. 7,303,650 discloses treating one side of the paper web with a bonding material according to a preselected pattern and creped from a creping surface. Through the process, a two-sided tissue web is formed having a smooth side and a textured side.
The aforementioned U.S. Patents which are hereby incorporated by reference. However, in the event of any conflict between such patents and this document, the contents of this document take precedence.